I know Ford's G heads were superior to the Cs, and in turn the Cs flowed better than the Bs. But do any hard numbers exist? Or, is anyone able to put this into better context? For example, wouid a set of professionally ported and polished C heads be equivalent to a stock set of G heads?

You would still have different size valves and compression ratios.

Ol'ford nutCentral Iowa

56 Vic w/292 & 4 spd.

At high revs, Cs flow as well (smaller valves, but less shrouding). Port & polished C would likely surpass stock G flow, but also lower CR due to larger chamber.

6 VOLTS/POS. GRD. NW INDIANA

4 or 5 years ago, Bruce Young gave some numbers in the Y Mag.  As I recall 113s did 185 cfm, G's 180 cfm, and C's 170 cfm, stock.  Maybe someone else has a photographic memory.

Mike, located in the Siskiyou mountains, Southern, OR 292 powered 1946 Ford 1/2 ton, '62 Mercury Meteor, '55 Country Squire (parting out), '64 Falcon, '54 Ford 600 tractor.

The upper port of almost any Y-Block head can be ported into the 210-215CFM range. The G, -113 and -471 heads can be ported to around 225CFM with 1.94" and 230's with 2.02" for both upper and lower. The problem with the less desirable heads is the lower. I've tried every trick I can think of and most won't reach 200CFM. The lower on the C head is one of the worst. High 190's is the best I've found. The C1AE can be made better with good porting and 1.88" valve,1.94" cut down to 1.88" to avoid spark plug interferrence. 

http://ford-y-block.com 

20 miles east of San Diego, 20 miles north of Mexico

Thanks gentlemen for your input.

John, do you believe the stacked head port configuration which was supposed to increase turbulence really had any benefit? Did the stock Gs deliver evenly between uppers and lowers? Thanks.

Well, yes and no. At low rpm the original head design probably kept the air/fuel well mixed and helped reduce detonation and may have improved fuel mileage. As the rpm increased the bends and sharp edges hindered flow and made the engine inefficient above 4500 rpm. The squish area was also exagerated in the Y-Block design with the valves pushed over the deck surface. Most performance engines try to place the valves as close to the center of the cylinder bore as possible. Again, good for low rpm use but not the best for performance.

Maybe too much of a good thing from a performance stand point but they weren't trying to design a race engine. Luckily the bottom end is stout enough to take performance abuse. The heads and intake manifold can be improved to much higher levels.

I will say that the stacked ports lock a designer in a box. I found there are definite limits to what can be done with the ports even when building a new head. The biggest problem is that the lower port cannot rise significantly before it is out from under the upper port. You must elevate the lower port floor to get the port to make the 90+ degree bend to the valve seat. If fact, this is the biggest problem with the 1955-56 heads. The lower floor is a simple arc that never gets very high and approaches the valve seat at too low an angle. You want the port to approach the valve at close to 90 degrees and this can't be done with the 55-56 heads. The later heads were greatly improved in this area.

The lower port is the most compromised by the design so we basically made a lower port that worked well and fit the upper port around it. With the stock gasket opening I think that around 270CFM is going to be very close to limit. Only time will time tell.

http://ford-y-block.com 

20 miles east of San Diego, 20 miles north of Mexico

With numbers that close, I would be more inclined to spruce up an existing head than go out of my way to find a better one.


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People should not be afraid of their government, a government should be afraid of the people.

--Alan Moore

I’m not John but I’ll add that the turbulence has more to do with the valve placement and combustion chamber design than the intake port layout in this particular case.  The small cylinder bores on the Y simply compounds the issue.  The stacked port design did allow the engineers at the time to use intake ports that had a larger cross sectional size as opposed to using ports that were placed side by side.  This was in part due to the pushrod placement and having to fit the ports between the pushrods.

The ports being stacked also made it easier to make each intake runner more equal in length from the carb to the valve which in turn allows the engine to produce a higher peak torque value.  Where an engine has unequal length intake ports, the average torque value ends up being lower.

Lorena, Texas (South of Waco)

I have to say I find all this fascinating.